RRB JE GK Questions 2026

Hooke found that so long as a body is not strained beyond its elastic limit, the restoring force per unit area rises in step with the fractional deformation, and the constant ratio of the two is called the modulus of elasticity.

In ordinary matter most atoms sit in the lower energy level, so light passing through is absorbed more than it is amplified.

When a material becomes superconducting it pushes the magnetic field out of its interior and behaves as a perfect diamagnet, an effect reported by Meissner and Ochsenfeld in 1933; it is the reason a small magnet can be made to hover above a cooled superconductor, as in magnetic levitation demonstrations.

The Dutch physicist Kamerlingh Onnes, who had already succeeded in liquefying helium, cooled mercury with it in 1911 and found that its electrical resistance disappeared completely below about 4.2 kelvin, the first observation of superconductivity.

Coherence means that the waves in the beam keep a constant phase relationship, so crest marches with crest; this is a direct result of stimulated emission, since each new photon is emitted in phase with the photon that caused it, and it is what makes holography and interference work with…

Maiman built the first operating laser in 1960, using a rod of synthetic ruby, that is chromium ions in aluminium oxide, pumped by a flash lamp, and it emitted pulses of deep red light.

The device works by stimulated emission, in which a photon passing an excited atom makes it fall to a lower level and emit a second photon identical in frequency, phase and direction, so one photon becomes two and the light is amplified.

The work function of a metal is the least energy needed to free an electron from its surface, and it is equal to Planck's constant multiplied by the threshold frequency of that metal; caesium and potassium have low work functions, which is why they respond to visible light.

By Einstein's photoelectric equation, the photon gives energy equal to Planck's constant times the frequency, part of which is spent as the work function, so the maximum kinetic energy left with the electron rises with frequency and is independent of how bright the light is.

The citation for the prize refers to his services to theoretical physics and especially to his discovery of the law of the photoelectric effect, the equation in which the energy of a photon equals the work function plus the maximum kinetic energy of the emitted electron.

In 1887, while studying the sparks produced across a gap between two electrodes, Hertz noticed that the spark passed more easily when ultraviolet light fell on the electrodes, which was the first observation of the photoelectric effect; Hallwachs and Lenard then studied it systematically.

The Minister of State said the operational metro network had expanded from that figure in 2014 to more than 1,185 km across 26 cities, with work under way on a further 998 km, so three numbers travel together in this question and they are easy to mix up.

The theme guided the whole programme, which looked at improving access within cities, integrating transport infrastructure and using digital technologies to raise the quality of urban life, and the opening session carried the same title in its conclave form.

The two-day conference was inaugurated there by the Union Minister of State for Housing and Urban Affairs, Shri Tokhan Sahu, in the presence of the state's Housing and Urban Development Minister, and it was the first time the city had hosted this annual event, which is a detail worth noting.

For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.

The Centre of Excellence at IIT (BHU), Varanasi has been given a brief in communication technology: wireless communications, quantum technologies, cybersecurity and communication systems driven by artificial intelligence, with advanced research in 5G Advanced and 6G technologies, very large-scale Multiple-Input Multiple-Output systems, sensing merged with communication, AI-native networks and devices…

The Centre for Development of Telematics, or C-DOT, is the research and development centre of the Department of Telecommunications, which is a department of the Ministry of Communications, and it is in that capacity that it signed the agreement for a Centre of Excellence at IIT (BHU), Varanasi.

The Centre for Development of Telematics signed a Memorandum of Understanding with the Indian Institute of Technology (BHU), Varanasi to establish its sixth Centre of Excellence, and the signing was followed by the formal opening of the centre on the campus.

The law states that for a mixture of gases that do not react, the total pressure is the sum of the partial pressures each gas would exert if it alone occupied the whole volume at the same temperature.

The root mean square speed follows from the kinetic gas equation and equals the square root of three RT divided by the molar mass, or equally the square root of three times the Boltzmann constant times the temperature divided by the mass of one molecule.